1. Field of the Invention
The present invention relates to an integrally combined intake manifold/surge tank structure (hereinafter, a composite intake manifold) composed of a plurality of molded members, for an internal combustion engine.
2. Description of Related Art
Recently, to improve torque and power characteristics at low and medium engine speeds, a longer intake passage between a surge tank and a cylinder (hereinafter, an intake port) of an internal combustion engine has been needed. To arrange a long intake port in the limited space of an automobile engine compartment, it is useful to wind the intake port in the form of an arc, as disclosed in Japanese Utility Model Publication SHO 61-76119.
However, there is a problem with the above-noted conventional intake port structure.
More particularly, in order to manufacture a curved intake port by molding aluminum or synthetic resin, it is necessary to use a molding core having a complicated structure, resulting in manufacturing cost increases.
Another method for manufacturing an intake manifold from a plurality of molded members is disclosed in SAE-930087. However, in this type of conventional composite intake manifold, the intake port is straight. If the straight intake port is arranged in a limited space, it will be necessarily short.